Insulated pipe is used to transport fluid that is hotter or colder than the ambient environment. The insulation commonly used for residential, commercial and light industrial pipe is made from fiberglass. Such insulation is cylindrical and wrapped with paper or fabric and frequently with aluminum foil in such a manner that individual lengths upon like clam shells around a hinge of paper or fabric. The insulation normally comes in three-foot lengths and it normally has a bent-back paper or fabric tab adjacent the opening between the two semi-cylindrical pieces that is provided with pressure-sensitive adhesive so that when the two cylindrical halves are placed around a pipe and brought together the tab can be adhesively connected to the other cylindrical half. The abutting ends of three-foot cylindrical pieces, after they are placed around the pipe, are connected together with a circumferencially wrapped piece of adhesive tape to provide virtually continuous insulation and a virtually continuous vapor barrier provided by the aluminum foil that is present both in the wrapping around the insulation and in the tape sealing abutting edges together.
In some applications insulation is made of stiff, chalky mineral material. Such insulation also comes in the shape of predetermined lengths of half-cylinders and it is also installed around pipes b placing two half-cylinders together around the pipe and holding them in place with wires after which they are wrapped in canvas, paper, foil or other material to hold them firmly in place, to seal all cracks and in most cases to provide a vapor barrier.
Long horizontal runs of pipes are supported with hangers that ar usually in the form of metal strips suspended from beams. The metal strips may be bent to conform with the circumference of the insulation around the pipe being supported or they may be straight horizontal stripe upon which one or more insulated pipe is placed. Hangers are normally spaced between 10 and 15 feet apart so long runs of pipe will be supported by man hangers.
Fiberglass pipe insulation is easily crushed or compressed at a position where it is supported by a pipe hanger. When insulation is crushed or compressed it looses some of its insulating value and it may be subject to deterioration because of vibration or thermal expansion and contraction. The brittle mineral insulation is also eroded where it is supported on hangers because of the weight of the pipe and thermal expansion and contraction. To avoid damage to insulation where it is supported on a hanger, pipe supports are frequently used. Some pipe supports ar semi-cylindrical pieces of metal that are usually approximately nine inches long. They are placed beneath the insulated pipe where it contacts the hanger. Another frequently used pipe support is a piece of insulation having an inside diameter approximately the outside diameter of the insulated pipe being supported. Pipe supports of this nature spread the weight of the supported, insulated pipe over a greater area to diminish crushing or deterioration of the insulation. They are difficult to install and at best they diminish the destruction of the insulation or its insulating value but not completely eliminate it.